If you look through the FAQ, there are a number of old posts dealing with this. Two of the more helpful for your would be:

What motivated the Franks to go on the 1st Crusade? (Although as my comment in this thread may be misleading, as noted therein, outside its original context, I should note that it was originally written for this thread: What motivations, other than religious devotion, were there for crusading lords and knights?)

For a more extensive bibliography, have a look at this thread:

What kind of specific examples/evidence exists to support the idea that the Crusades were motivated more by the prospect of collateral wealth rather than religious goals in the Holy Land?